Laryngeal Electromyographic Activity in Adductor and Abductor Spasmodic Dysphonia Vocal symptoms in spasmodic dysphonia (SD) range from strain-strangle phonation and glottal-stop phonatory breaks of adductor SD to breathy phonation and aspirate phonatory breaks of abductor SD. Many SD subjects show both symptom types. Heterogeneity in vocal symptoms contributes to controversy surrounding the etiology(s) of SD. Acoustic/perceptual analyses of vocal ... Research Article
Research Article  |   June 01, 1991
Laryngeal Electromyographic Activity in Adductor and Abductor Spasmodic Dysphonia
 
Author Affiliations & Notes
  • Ben C. Watson
    The University of Texas at Dallas/Callier Center
  • Steven D. Schaefer
    The University of Texas Southwestern Medical Center at Dallas
  • Frances J. Freeman
    The University of Texas at Dallas/Callier Center
  • James Dembowski
    The University of Texas at Dallas/Callier Center
  • George Kondraske
    The University of Texas at Arlington
  • Rick Roark
    The University of Texas Southwestern Medical Center at Dallas
  • Requests for reprints should be sent to Ben C. Watson, PhD, 1966 Inwood Road, Dallas, TX 75235.
Article Information
Speech / Research Articles
Research Article   |   June 01, 1991
Laryngeal Electromyographic Activity in Adductor and Abductor Spasmodic Dysphonia
Journal of Speech, Language, and Hearing Research, June 1991, Vol. 34, 473-482. doi:10.1044/jshr.3403.473
History: Received March 9, 1990 , Accepted August 17, 1990
 
Journal of Speech, Language, and Hearing Research, June 1991, Vol. 34, 473-482. doi:10.1044/jshr.3403.473
History: Received March 9, 1990; Accepted August 17, 1990

Vocal symptoms in spasmodic dysphonia (SD) range from strain-strangle phonation and glottal-stop phonatory breaks of adductor SD to breathy phonation and aspirate phonatory breaks of abductor SD. Many SD subjects show both symptom types. Heterogeneity in vocal symptoms contributes to controversy surrounding the etiology(s) of SD. Acoustic/perceptual analyses of vocal symptoms are inconclusive in resolving this controversy. This investigation moves the search for distinguishing features of adductor and abductor SD to the level of neuromuscular control and analysis of intrinsic laryngeal muscle (adductor and abductor) activity. Subjects rated perceptually as primarily adductor or abductor SD sustained production of vegetative gestures and isolated speech sounds (/i/ and /s/). Qualitative and quantitative analyses of electromyographic signals recorded from thyroarytenoid (TA) failed to differentiate SD subjects by symptom type. Analysis of TA and posterior cricoarytenoid (PCA) activity in one abductor SD revealed high levels in both muscles during production of the voiced vowel. Data suggest that a possible explanation for symptom heterogeneity in SD is the relation between disrupted neuromotor input to laryngeal muscles and reflexive or conscious compensations constrained by laryngeal biomechanics.

Acknowledgment
Funding for this study was provided by NIH Grant DC00410.
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